Transport of Oxygen in Blood and tissue fluids

Transcription

Transport of Oxygen in Blood and tissue fluids
Transport of Oxygen in Blood
and tissue fluids
DR AMNA TAHIR
DIFFUSION OF OXYGEN FROM THE ALVEOLI
TO THE PULMONARY CAPILLARY BLOOD
• PO2 Of gaseous oxygen in the alveoli = 104 mm Hg
• PO2 Of venous blood entering the pulmonary
capillary at its arterial end = 40mm Hg
• Initial pressure difference= 104-40= 64mm Hg
• PO2 Of the blood rises to that of alveolar air by
the time the blood has moved a third of the
distance through the capillary
• Uptake of oxygen by the pulmonary blood
during exercise
• Greater safety factor
Up take of oxygen by
the pulmonary blood
TRANSPORT OF OXYGEN IN THE
ARTERIAL BLOOD
• 98 % OF the blood that enters the left
atrium with PO2 = 104 mmHg
• 2% OF the blood has passed the bronchial
circulation ( SHUNTED BLOOD) with PO2 =40
mmHg
• Venous admixture of blood
• PO2 of the blood pumped by aorta = 95
mmHg
DIFFUSION OF OXYGEN FROM THE
PERIPHERAL CAPILLARIES INTO THE
TISSUE FLUID
• PO2 at the arterial end= 95 mmHg
• PO2 in the interstitial fluid that surround
the tissue cells= 40mmHg
• Tissue PO2 is determined by 2 factors
1. Rate of oxygen transport to tissues in the
blood
2. The rate at which the oxygen is used by
the tissues
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DIFFUSION OF OXYGEN FROM THE
PERIPHERAL CAPILLARIES TO THE
TISSUE CELLS
Intracellular PO2 ranges 5-40 mmHg
Average 23 mmHg
1-3 mmHg is required
Larger safety factor
ROLE OF HEMOGLOBIN IN OXYGEN
TRANSPORT
• 97% is carried in chemical combination
with Hb
• 3% is transported in dissolved state
• Reversible combination of oxygen with Hb
• Oxygen-Hemoglobin Dissociation curve

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